1. Field of the Invention
The present invention relates to an image forming apparatus comprising a latent image carrier for carrying a latent image on an endless moving surface and a latent image writing device movable between an operation position where the write operation is performed for writing a latent image on this surface and a retreat position where the write operation is not performed. In addition, the present invention relates to a processing unit and latent image writing device mounted in this image forming apparatus.
2. Description of the Related Art
In the widely adopted conventional electrophotographic-type image forming apparatus configuration a latent image is written on a latent image carrier such as a uniformly charged photosensitive body by means of a latent image writing device such as a laser writing device that performs an optical scanning operation employing a laser beam. Depending on the layout thereof, the latent image writing device of this kind of image forming apparatus serves as an obstruction to the maintenancability of the various peripheral devices including the latent image carrier and the development device arranged in the periphery thereof.
Japanese Patent No. 2849978 describes an image forming apparatus in which a latent image writing device is supported by means of an open/close cover openable relative to a fixed cover which constitutes a part of the box-shaped body of the image forming apparatus, the latent image writing device being widely separated from the latent image carrier accompanying the opening of the open/close cover. According to this configuration, the latent image writing device is caused to retreat from a position opposing the latent image carrier accompanying the opening of the open/close cover exposing the latent image carrier and the peripheral devices thereof to the exterior whereupon, accordingly, the maintenancability thereof is improved.
However, in this image forming apparatus, error in the relative positioning between the latent image writing device supported by the open/close cover and the latent image carrier supported by the fixed cover is produced as a result of the play and so on that exists in the open/close cover relative to the fixed cover. An additional problem inherent thereto pertains to a drop in write positional accuracy of the latent image writing device caused by this error. This same problem is liable to occur due to play of the latent image writing device in configurations in which the latent image writing device does not move accompanying the opening and closing of the open/close cover but rather the latent image writing device is moved independently or together with some other member.
Technologies relating to the present invention are also disclosed in, e.g.:
Japanese Laid-open Patent Application. No. H04-110874,
Japanese Laid-open Patent Application. No. H06-102742, and
Japanese Laid-open Patent Application. No. H07-333541.